Generally, lighting apparatuses, such as a street light and a floodlight, have been designed and manufactured to have a proper light distribution type so that they can efficiently light an object to be illuminated.
The lighting apparatus is designed such that a high pressure sodium lamp, a mercury vapor, a metal halide lamp, or a typical electric bulb, is used as a light source and light from the light source is reflected from a reflection plate to form a light distribution type suitable for an object to be illuminated.
In particular, a floodlight has been used widely in many fields of a building, an advertisement plate, a working site, a stadium, and a parking lot as well as an advertisement tower. In the floodlight, a reflection plate having a parabolic shape and a light source are provided inside a lamp housing.
The floodlight is designed to have a proper light distribution type in consideration of a distance from an object to be lighted and the lighting area of the object. The distance between a reflection plate and a light source, such as a high pressure sodium lamp, a mercury vapor or a metal halide is adjusted, or the angle and shape of the reflection plate are adjusted to form a desired light distribution.
Meanwhile, the lighting apparatus provided with the light source, such as a high pressure sodium lamp, a mercury vapor or a metal halide, is able to obtain various light distributions by adjusting the shape and angle of the reflection plate or reflector. However, the brightness and diffusion range of many kinds of lamps used as a light source, such as a high pressure mercury lamp, a fluorescent lamp, and a sodium lamp are fixed when the lamps are manufactured initially. Therefore, it is difficult for the user to arbitrarily adjust the brightness of the diffusion range. In addition, they have a short life span and high power consumption.
Recently, in consideration of the aforementioned drawbacks, a lighting apparatus has been proposed which uses LEDs (light emitting diodes) as a light source. With the development of technique, light emitting diodes with low power consumption and high brightness have been developed and come into widespread use.
However, the light emitting diode has a substantially permanent life span, as compared to the commonly used/conventional lamps according to the related art, and the brightness of light emitted from the light emitting diodes is determined by a combination of the light emitting diodes. When light distribution is formed by the reflecting plate, a light distribution area is small, and brightness is low. In addition, there are limitations in forming sufficient light distribution to effectively illuminate an object to be light.
Further, since it is difficult to effectively dissipate heat generated from a plurality of light emitting diodes, emission efficiency is lowered due to heat, which results in the damage of parts.
Furthermore, as shown in FIGS. 1 and 2, for example, most commonly used floodlights, which use light emitting diodes, are formed in a circular or rectangular shape, and includes a lamp housing member 1 having a flat lamp mounting surface on the inner surface and light emitting diode modules 2 which are provided on the flat lamp mounting surface la behind of the lamp housing member 1.
Therefore, the floodlight according to the related art has a problem in that it does not form various light distributions, and thus there are limitations in the installation position of the floodlight and objects to be illuminated.